Heat exchanger construction



June 24, 1969 R 3 ET AL 3,451,473

HEAT EXCHANGER CONSTRUCTION Filed April 11, 1967 Sheet of 2 0 VENT Z5 OVERBOARD June 24, 1969 R 3, ET AL 3,451,473

HEAT EXCHANGER CONSTRUCTION Filed April 11, 1967 Sheet U.S. Cl. 165-166 4 Claims ABSTRACT OF THE DISCLOSURE Iudiciously located passages in the core of a heat exchanger are provided to vent the escapement of obnoxious or toxic fluid utilized therein for heat exchange relationship.

Background of the invention This invention relates to plate and fin type heat exchangers and particularly to the construction of the core which is adapted to vent out escaping obnoxious or toxic fluid which is in indirect heat exchange relationship so that is does not comingle with the other fluid in heat exchange relationship therewith.

Since the advent of high speed aircraft, it has ben desirable to utilize the fuel as a heat transfer medium for the air which is eventually delivered to the cabin to be breathed by the occupants thereof. Heretofore plate and fin type heat exchangers have been adapted to prevent contamination of the air which may occur in the event of leakage in the toxic fluid or obnoxious fluid passages. The customary method is to provide barrier vent or dummy passages to surround the fuel passage which barrier passages communicate at the respective corners of the heat exchanger which is generally contoured so as to adapt dummy headers for bleeding off the obnoxious fuel. Generally, the opposing corner would communicate with fuel or air in the event of leakage of either medium. Thus, for a leakage in the air or fuel passage there would be a vent header mounted on the corner of the core to accommodate it.

I have found that I can eliminate the corner headers entirely by judiciously locating passages communicating internally of the core of the heat exchanger in such a manner as to conduct the leakage of either fuel or air to a single vent. Thus, the corner headers are entirely eliminated which not only results in a simpler constructed heat exchanger but significantly reduces the cost thereof.

Summary of invention A primary object of the present invention is to provide an improved plate-fin heat exchanger that provides means for venting contamination in the event of leakage therein.

In accordance with a further aspect of the present invention, passages are provided in the parting sheets and are judiciously located to provide a direct passage to a single boss formed on the heat exchanger for venting the escaped fluid to a lower pressure source.

A still further object of this invention is to provide a heat exchanger constructed core characterized as being relatively simple to manufacture and assemble and economical to build, which heat exchanger is adapted to vent escapement of heat exchange fluid in the event of a leakage therein.

Brief description of the drawings Other features and advantages will be apparent from the specification and claims and from the accompanying drawings which illustrate an embodiment of the invention.

FIGURE 1 is a partial sectional view of the core of United States Patent 3,451,473 Patented June 24, 1969 the heat exchanger illustrating this invention and in which the headers have been omitted for the sake of clarity.

FIGURE 2 is a partial sectional view taken along the line 2-2 of FIG. 1.

FIGURE 3 is a partial sectional view taken along the line 33 of FIG. 1.

FIGURE 4 is a partial sectional view taken along line 44 of FIG. 1.

FIGURE 5 is a partial sectional view taken along the line 5-5 of FIG. 1.

FIGURE 6 is a view in perspective illustrating the flow path schematically but the dimensions of which do not necessarily reflect the proportions of the heat exchanger shown in FIGS. 1-5.

FIGURE 7 is an exploded view in perspective illustrating a series of heat exchange plates and fins with closure bars separated to show the several fluid flow paths through the heat exchanger.

The invention can best be understood by referring to the preferred embodiment illustrated in FIGS. 1-6 which shows generally a plate-fin type of cross flow heat exchanger illustrated by the general reference numeral 10 consisting of top and bottom plates 12 and 14 and the stacked passages formed therebetween. As can be seen from FIG. 1 the heat exchanger comprises alternately dummy passage 16 formed between the bottom plate 14 and the parting sheet 18, fuel passage 20 formed between the parting sheet 18 and 22, dummy passage 24, parting sheet 26, air passage 28, parting sheet .30, dummy passage 32, parting sheet 34, fuel passage 36 and continuing in this manner until the entire core comprises the number of fuel and air passages desired.

It will be obvious from the foregoing that a dummy passage is adjacent the top and bottom sides of the fuel passage. Looking at the moment to FIG. 5, it can be seen that adjacent the edges of the fuel passage 20, for example, a pair of spaced closure bars 38 and 40 are mounted parallel along the outer edge thereof. Similar spaced closure bar are mounted on the opposite edge so that dummy passages encircle the fuel passage, except where the core communicates with the fuel headers.

Looking at the fuel passage as is shown in FIG. 2, fins 42 are suitably mounted therein and sandwiched between the parting sheets as is shown in FIG. 5 of passing the fuel directly through the core is fed from the header 44 which is partially shown for the sake of convenience and clarity. It will be noted that the closure bars 46 and 48, which are spaced in similar manner as were 40 and 38, abut against the parting sheet in the passage immediately below which parting sheet has formed therein a plurality of spaced holes 50. These spaced holes are in communication with the channel formed between the closure bars 46 and 43.

The dummy passages as shown in FIG. 3 may contain straight-through fins 54 instead of the wave-type fins illustrated by reference numeral 42 for the sake of simplicity and cost in the manufacturing thereof. It will be noted that the fuel header 44- and the air header 56 do not communicate with the passage since it is blocked off by the closure members 58 and 66. The parting sheet directly above in the adjacent pass is in communication as was mentioned above with the channel defined between spaced closure bars 46 and 48. Iudiciously located spaced holes 59 are formed in the parting sheet immediately adjacent the vent passage. Viewing the next adjacent passage which is an air passage, see FIG. 4, which is in communication with header 56, spaced closure bars 60 and 62 form channel 64 which is in communication with the next adjacent pass through the openings 68 which are judiciously located in a manner similar to the holes in the next adjacent passages. Thus it is apparent that should a leak occur in the core adjacent either the parting sheets or the closure bars, escapement fluid would be directed to the space between the channels or in the vent passages adjacent thereto. The escapement fluid would then be directed from pass to pass away from where fuel or air is in heat transfer relationship until it eventually is directed to the last dummy passage which is in communication with an opening formed in vent boss 69. Here the escaped fluid is directed to a low pressure source and in the application of an aircraft it would presumably be directed overboard of the aircraft.

The path of the escaped fluid can best be appreciated by referring to FIG. 6 which illustrates six adjacent passes in the heat exchanger core starting from the bottom pass which is in communication with the vent. Hence, looking at FIG. 6, the vent, being identified by numeral 70, is mounted in any suitable way, to the bottom plate 72, which together with parting sheet 74, defines the first vent passage 76. Sandwiched between the parting sheets 74 and 78 is the fuel passage 80. Sandwiched between parting sheet 82 and parting sheet 78 is another vent passage 84, and sandwiched between parting sheets 86 and 82 is air passage *88, and between parting sheets 92 and 86 is another vent passage 96, and between parting sheets 94 and 90 is again another fuel. Space closure bars are mounted on the outer edge of passage 96 as schematically illustrated by closure bars 98 and 100. Likewise, space closure bars oriented at 90 angle relative to closure bars 98 and 100 are mounted on the edge of the air passage 88, just underneath closure bars 108 and 110 mounted on the edge of fuel pass 80. Assume for illustration purposes that fuel escapes through an opening and leaks past the closure bar 98. From there it is directed to the channel formed between outer edges of parting sheets 90 and 94 and the closure bars 98 and 100. The opening 112 is in communication with the vent passage next adjacent thereunder which contains judiciously located openings as illustrated by reference numeral 114 which is in communication with the space defined by the end closure bars 116 and 118 mounted on the edge of the air passage 88 is then directed to the opening 120 where it directs the fluid to the dummy passage 84 which also contains judiciously located openings 124 which are, in turn, in communication with the channel defined by the edges of parting sheets 78 and 74 and the space closure members 108 and 110. Other judiciously located openings are formed in parting sheet 74 placing that opening in communication with the vent passage 76 directly thereunder. The escapement fluid eventually is vented overboard through opening 128 formed in boss 7 What has been shown by this invention is the judicious location of openings in the parting plate of adjacent passages for communicating escapement fluid directly away from the fluids that are in heat exchange relationship with each other. The escapement fluid is directed overboard to a low source so that it is unable to escape into the air passage which eventually directs air to the cabin of the aircraft which air if contaminated could be harmful to the occupants therein.

It should be understood that the invention is not limited to the particular embodiment shown and described herein, but that various changes and modifications may be made.

What is claimed is:

1. A heat exchanger of the type having a plate and fin core adapted to place a first medium and a second medium in indirect heat exchange relation comprising,

at least one pass having parallelly spaced plates and fins disposed therein defining open-ended channels for receiving and conducting one of said mediums,

dummy passage means also having parallelly spaced plates sandwiching said pass adapted to receive escapement of the medium in the event of leakage,

a pair of parallelly spaced closure bars mounted adjacent the side edges of the fins of said pass, and between said parallelly spaced plates,

a discharge port,

openings in said parallelly spaced plates adjacent the space between said closure bars for interconnecting said dummy passage means through the space between said closure bars and being in communication with said discharge port.

2. A heat exchanger as defined in claim 1 wherein said dummy passage means includes corrugated fins sandwiched between said parrallely spaced plates.

3. A heat exchanger as defined in claim 2 wherein said heat exchanger includes a bottom plate, a parting sheet parallelly spaced therefrom and closure bars sandwiched therebetween at the edegs thereof, an opening formed in said bottom plate communicating with the space between said bottom plate and said parting sheet.

4. A cross-flow heat exchanger of the type that has a top and bottom plate,

parallelly spaced parting sheets disposed between the top and bottom plate,

corrugated fin elements sandwiched between the parting sheets defining therewith straight-through channels,

adjacent channels defining passes in a predetermined sequence such that a dummy pass, a fuel pass, a dummy pass, an air pass constitute a repeatable pattern,

end closure bars at the side edges of said fins sealing the sides of said passes,

additional closure bars at the front and rear edges of said fins in the dummy pass completely sealing off said dummy pass,

parallelly spaced closure bars adjacent the end closure bars of each of said air and fuel pass defining therewith side dummy passes,

openings in said parting sheet intermediate said spaced closure bars communicating said adjacent dummy passes with side dummy passes,

headers mounted externally of said core for admitting and discharging fuel and air to the respective air and fuel passes,

and an opening in said bottom plate communicating with a dummy pass formed adjacent thereto and in communication with each of said dummy passes and said side dummy passes.

References Cited UNITED STATES PATENTS 2,846,198 8/1958 Sturges 16S70 3,150,028 9/1964 Wennerberg -466 X 3,229,764 1/1966 Ware 165-167 MEYER PERLIN, Primary Examiner.

THEOPHIL W. STREULE, Assistant Examiner.

US. Cl. X.R. 165-70 

